88“ Count Rumford's Inquiry concerning 
If the heat, or any considerable part of it, were produced in 
consequence of a change in the capacity for heat of a part of 
the metal of the cylinder, as such change could only be super- 
ficial , the cylinder would by degrees be exhausted; or the 
quantities of heat produced, in any given short space of time, 
iv 
would be found to diminish gradually, in successive experi- 
ments. To find out if this really happened or not, I repeated 
the last-mentioned experiment several times, with the utmost 
care ; but l did not discover the smallest sign of exhaustion 
in the metal, notwithstanding the large quantities of heat ac- 
tually given off. 
Finding so much reason to conclude, that the heat generated 
in these experiments, or excited , as I would rather choose to 
express it, was not furnished at the expence of the latent heat 
or combined caloric of the metal, I pushed my inquiries a step 
farther, and endeavoured to find out whether the air did, or 
did not, contribute any thing in the generation of it. 
Experiment No. 2. 
As the bore of the cylinder was cylindrical, and as the iron 
bar, (z;z,) to the end of which the blunt steel borer was fixed, 
Was square, the air had free access to the inside of the bore, 
and even to the bottom of it, where the friction took place by 
which the heat was excited. 
As 'neither the metallic chips produced in the ordinary course 
Of the operation of boring brass cannon, nor the finer scaly 
particles produced in the last mentioned experiments by the 
friction of the blunt borer, showed any signs of calcination, I 
jdid not see how the air could possibly have been the cause 
